In a cross-domain MultiProtocol Label Switching Traffic Engineering (MPLS-TE) and Generalized MultiProtocol Label Switching (GMPLS) network, due to requirements for management, geographic positions, and switching environments, the network may be divided into multiple domains and one domain is connected to another domain through a link between boundary nodes which egress and ingress the domains. This link connection is commonly referred to as a Label Switching Path (LSP) in a multi-domain network environment.
In the multi-domain network environment, two LSPs are usually configured for each bearer service. One LSP is called a working path and the other LSP is called a protection path (backup path), in case when the working path fails, the protection path is used for transmission of services. On the basis of this, the protection path configured for the working path is a path having the same source node and destination node as those on the working path, but having other nodes, links and Share Risk Link Group (SRLGs) etc. which are completely separated (different) from those of the working path.
For the cross-domain separation (disjoint) path computation method, the Internet communication protocol standard RFC5298 proposes two basic methods, one is sequential path computation and the other is simultaneous path computation. Herein, as a working path is computed prior to a protection path in the sequential path computation, nodes and links of a working path in each domain have been determined before a protection path is computed. At the same time, the protection path to be computed needs to satisfy a constraint condition that its respective nodes, links, and SRLGs are all separated from those of the working path. When there are some limitations, for example, nodes or links selected for the working path which is computed firstly are unreasonable, it will lead to a failure in computing a protection path which is separated from the nodes, links and SRLGs of the working path in a domain, thereby resulting in a failure in the cross-domain separation path computation. For the simultaneous path computation, a success ratio of the sequential path computation for acquisition of a cross-domain separation path is theoretically increased, but a domain sequence between a head domain and a tail domain of a cross-domain end-to-end path needs to be known in advance before this method is used.